Immune/Antihistamine Protocol

I posted a few days ago, but wanted to seek any advice people may have on timelines for an antihistamine/immune protocol with OTC meds and potentially prednisone(if I am able to access it)

Looking at incorporating Claritin, Pepcid, baby aspirin, and progesterone and wondering when to start each/how much to take/when to stop.

We are trying naturally (I apologize if this is the incorrect term for this) and I am likely to ovulate in the next week.

Our plan for progesterone suppositories is to start 3 DPO, but if anyone has any suggestions on the right dose, this would be helpful. The RPL clinic told me to not take it until after the positive pregnancy test, but I decided to instead take the advice of another clinic who said to start 3DPO. Last pregnancy (which was a partial molar), I started with 100mg per day until positive pregnancy test, then upped it to 400 per day (200 in morning/200 in evening).

As for the prednisone, we are still fighting to get a prescription for that. I have elevated Natural killer cells, so hoping that might help with that. Do most people take 10mg per day? When do you start/stop?

TLDR: when should I start baby aspirin, Claritin, Pepcid and progesterone? What about prednisone?